This invention relates to proximity sensing systems. More specifically, the invention is a self-activating system that alerts someone when an object or a person is left unattended in a motor vehicle or other dangerous environment.
In accordance with the present invention, a self-activating system is provided for alerting someone that an object or person has been left unattended as is the case when a child is left restrained or unattended in a car seat. The system includes a detector for sensing the presence and/or absence of the child in the car seat. Coupled to the detector is a transmission means for automatically transmitting one of a plurality of unique wireless signals. For example, the plurality of wireless signals may include a first signal when the child is in the car seat and a second signal when the child is removed from the car seat. Remotely located with respect to the transmission means is a receiving means capable of sensing the plurality of wireless signals, including the first signal and the second signal. The receiving means is possessed by the parent or other responsible caregiver who is also generally the driver of the vehicle in which the car seat is located. The receiving means is programmed to carry out a plurality of timing functions including a first timing function and a second timing function. The first timing function is enabled when the first signal is initially sensed. Once enabled, the first timing function times to a first interval or intervening period of time. At the completion of each first interval, the receiving means can implement a variety of actions. Specifically, the receiving means (i) continues the first timing function if the first signal is sensed indicating that the receiver is still in proximity to the child in the car seat; (ii) disables the first timing function if the second signal is sensed indicating that the child has been removed from the car seat; or (iii) enables the second timing function if neither of the first signal nor the second signal is sensed. The second timing function indicates that the responsible caregiver possessing the receiving means has ventured outside the range of the transmission means while the child is still located in the car seat. If enabled, the second timing function times to a second interval having a first time and a later second time. The receiving means issues a first alarm signal at the first time if neither the first nor second signal is sensed. However, the receiving means discontinues the first alarm signal if the first signal is sensed during the second interval indicating that the responsible caregiver (possessing the receiving means) has returned within the range of the transmission means while the child is still located in the car seat. Further, the receiving means issues a second alarm signal if the first signal is not sensed during the second interval. The second alarm signal is allowed to continue after the second time until the second signal is sensed. That is, the second alarm signal continues until the responsible caregiver (possessing the receiving means) has returned to the vicinity of the transmission and the child is removed from the car seat.